The invention relates generally to the art of biological catalytic reactor systems with mycelia of microorganisms, especially mycelial fungi, and more particularly to mycelial pellets having a support core and use thereof for biocatalytic conversions, as well as the preparation of the biologically active mycelial pellets.
Microorganisms have long been employed in the biocatalytic conversion of organic compounds. Exemplary of such conversions, to mention but a few, include conversion of simple sugars to useful products such as alcohols and organic acids; production of enzymes; synthesis of antibiotics and isomerization of sugars. Thus, the conversion of various sugars has to some degree involved the use of fungi, but such use has been generally limited to an unsupported vegetative mass. U.S. Pat. No. 4,127,447 describes a biocatalytic reaction involving a packed column packed with a support material to which have been attached the needed anaerobic microorganisms. U.S. Pat. No. 4,090,022, describes the use of porous cellulose beads to which active biological agents (e.g. enzymes) may be attached by means of chemical bonding. In each case the active agent is bonded to the support, thus necessitating preparation of the support for attachment of the desired agent.
The use of mycelial fungi in biocatalytic systems has been limited due to the difficulty in handling such masses. While supported mycelia would be desirable, no satisfactory method has been developed prior to the present invention, and methods to date require preparation of the support surface in order to attach the active agent. It is known that some mycelial fungi can form mycelial pellets in a conventional shaking culture. While such a pellet form is more desirable than the unshaped vegetative mass, the pellets suffer a number of disadvantages. For example, if placed in a column reactor, under flow pressure, the pellet may collapse and plugging will occur. Furthermore, handling and recovery of these pellets are hampered due to the weak physical properties of the pellets.
Since the discovery of the present invention, K. Gbewonyo and D. I. C. Wang have reported the growth of mycelial microorganisms on spherical diatomaceous beads (Abstract of Papers presented at 178th ACS Meeting, Washington, D.C., Sept. 10-13, 1979--American Chemical Society Division of Microbial and Biochemical Technology). The report describes the growth of Penicillium chrysogenum on porous celite beads resulting in the projection of hyphae outwards from the bead surface. No surface layer of structural integrity is reported.
In accordance with the present invention, we have discovered useful spherical shaped mycelial pellets which possess an inner rigid structural core which is surrounded by a porous webbed layer having structural integrity of a mycelial microorganism. The porous webbed layer thus forms a spherical encasement of structural integrity about the rigid core.
Accordingly, it is the primary object of the present invention to provide mycelial pellets having a core support surrounded by a porous webbed layer of structural integrity of a mycelial microorganism.
It is a further object of the present invention to provide an improved means for carrying out the biocatalytic conversions of organic compounds.
These and other objects of the present invention will become more apparent from the discussion which follows.